Climate change emergence over people’s lifetimes

The emergence of climate change from background variability is a useful metric for identifying changes in local climate which may affect people and ecosystems. Studies have found that equatorial regions, which are typically poorer, experience clearer climate change emergence over the observational record and in model projections. Here, we perform the first analysis of people’s experienced climate change relative to background variability, and we examine where people have already lived through an emergence of local warming. We calculate signal-to-noise (S/N) ratios and combine these with demographic data to compute local emergence of warming over human lifetimes. Younger people have typically experienced less clear emergence of a climate change signal over their lifetimes to date. Over a given time period, tropical, lower-income areas have experienced higher S/N than extratropical and typically higher-income areas. However, this is counter-balanced by the younger populations of these areas such that the median experienced S/N ratio is similar between the wealthiest and poorest parts of the world. Given projected ageing of low-income regions, it is imperative that substantial climate action is taken to avoid local climates becoming unrecognizable within human lifetimes.